A new optical sensor technology based on dyed polymer microspheres and self-assembled arrays will be developed to meet a range of specific commercial solvent and other hazardous chemical vapor-sensing needs. Sensors will incorporate solvatochromic fluorophores that exhibit large intensity and/or wavelength shifts in their fluorescence emissions when exposed to environments of different polarity. A specific aim of the project will be to explore the ability to generate a library of diverse sensors for use in the array, based on simple parallel syntheses involving the chemical derivatization of a single starting bead material. The sensing approach employs the self assembly of many thousands of microsphere sensors onto the face of an etched optical imaging fiber of approximately 1mm diameter. Beads will be recognized and classified after array assembly by their unique, self-encoded response pattern to a selected vapor pulse. This innovation offers the advantage of facile preparation of large numbers of inexpensive, and potentially disposable, sensor arrays. In addition, the high sensor redundancy inherent in the present design affords signal amplification opportunities through multi-based signal summing. PROPOSED COMMERCIAL APPLICATION A miniaturized, hand-held vapor-sensing device that is robust and reproducible has commercial appeal by any personnel that routinely encounter solvent-saturated environments. The commercial application of such a device may also extend to utilities as diverse as quality and process control in the food and beverage, chemical, fragrance and cosmetic, and automotive industries, with long-term potential in medical diagnostics, environmental monitoring, and land mine detection.